Since the middle of the nineteenth century phenol has been an important item of commerce. Initially it was recovered from coal tar, which was its only source for many years. As the demand for phenol increased, synthetic processes were introduced to make this chemical.
One of the earliest phenol processed was the so-called Raschig Process. First, benzene was oxychlorinated with hydrogen chloride and oxygen to produce chlorobenzene. Second, the chlorobenzene from the first step was hydrolyzed with water to form phenol and hydrogen chloride. By recycling the hydrogen chloride so produced to the first step, a self-contained process resulted.
The details of the Raschig Process are outlined in U.S. Pat. No. 1,963,761 U.S. Pat. No. 2,035,917 and U.S. Pat. No. 2,311,777. Although no longer in use, the Raschig Process proved to be a commercial success. The chief difficulties with the process involve the hydrolysis step. The hydrochloric acid produced is extremely corrosive and requires expensive equipment to handle. The hydrolysis reaction is reversible, thus limiting the conversion of chlorobenzene to phenol. Lastly, by-product formation adds to the cost of manufacture.
With the drawbacks of the Raschig Process in mind, the present invention was conceived as an improved process for the production of phenol. The objects of the present invention includes a process that meets the environmental and economic needs of manufacturers. These objects as well as other features and advantages will be apparent from the following description and the figure, which is included.